In the depressed economy of the 1930s, Harlingen leaders sought federal funds by offering land for a military airfield, and in May 1941 the U.S. War Department accepted the city's offer of 960 acres for a military airfield and flexible gunnery school as the nation prepared for World War II. The area's flat topography, impractical for artillery training, proved ideal for aircraft operations, and additional coastal land was obtained for combat maneuvers. The Harlingen Army Gunnery School received its first students in August 1941, and by 1944 the facility had grown to nearly 1,600 acres, accommodating up to 9,000 trainees at peak times; those stationed there included Women Airforce Service Pilots. The field closed in 1946, and after the war many buildings were sold to local residents and businesses. In April 1952, during the Korean conflict, the government reactivated the installation as Harlingen Air Force Base with the primary mission of training navigators. New facilities included a hospital, and residents on and off the base followed events through the Sun Lines newspaper. In 1961 the U.S. government announced closures that included Harlingen, and by June 1962, when the last class graduated, more than 13,000 navigators had completed training there. The shutdown removed millions of dollars from the local economy and severely affected the city. The former base later served as a regional airport, becoming Valley International Airport in 1970, while other portions were used for an industrial air park, the Texas State Technical Institute, the Marine Military Academy, and the Rio Grande Valley Museum.